This study examined the association pattern of two snapping shrimp species that inhabit burrows at exposed rocky shores of the Chilean Pacific coast. The two species Alpheus inca and Alpheopsis chilensis were frequently found to share the same burrows. In most burrows an heterosexual pair of each species was found. A strong positive correlation between the body length of female and male conspecifics cohabiting in a burrow was found both for Alpheus inca and for Alpheopsis chilensis. Similarly, a positive correlation existed between the mean body length of Alpheus inca and that of Alpheopsis chilensis occurring together in one burrow. Thus, a size-relationship between burrow cohabitants exists both in the intra-specific as well as in the inter-specific association of these shrimps. Most females, regardless of their reproductive stage, were accompanied by males. Within a particular burrow, females of the two species often were in the same reproductive stage, i.e. both were with embryos in a similar developmental stage, or both were without embryos. These data suggest that male and female conspecifics, as well as the pairs of the two species, remain together in the same burrow for relatively long time periods. It is proposed that the intra-specific communication system of snapping shrimp facilitates the development of inter-specific associations, such as the one reported herein.